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    <h1>篮球从5米高的地方掉下来，每次弹起的高度是原来的30%，经过几次弹起，篮球弹起的最终高度小于0.1米</h1>
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<script>
    var m = 5;
    for (var i = 0;; i++) {
        m -= m * 0.3;
        if (m < 0.1) {
            document.write(i);
            break;
        }
    }
</script>

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